The entire disclosure of Japanese Patent Application No. 2002-90987 filed on Mar. 28, 2002, including specification, claims, drawings and summary, is incorporated herein by reference in its entirety.
1. Field of the Invention
This invention relates to a plate handling method and a plate handling apparatus for a plate cylinder of a printing press.
2. Description of the Related Art
For a web rotary press or the like, in which a plurality of printing units are arranged, various proposals have been made for an automatic plate changer, which automatically mounts a printing plate (hereinafter referred to simply as a plate) at a predetermined position of a plate cylinder of each of the plural printing units, and automatically removes the plate from the plate cylinder.
For example, Japanese Patent No. 2704558 discloses a method for changing plates in a printing press having a plurality of printing units different in the rotation phase of each plate cylinder, whereby even when plate removal in one of the printing units is taking place, a plate removal operation is performed in the other printing units, thus shortening the plate changing time.
If an error occurs during the plate removal (or plate supply) operation by the automatic plate changer, the plate being removed may be caught by ink form rollers and damage a blanket or the roller, unless the plate changing procedure is promptly stopped.
Thus, Japanese Unexamined Patent Publication No. 1999-170486 discloses a feature in which a sensor is provided for detecting an abnormality in the plate being removed during the plate removal, and when the abnormality in the plate removal is detected by the sensor, a printing press is shut down.
In the plate changing method disclosed in Japanese Patent No. 2704558, however, the rotation phase of the plate cylinder is different among the printing units, as stated above. Therefore, in the printing units showing no abnormality in the plate removal at the time when an abnormality in the plate removal was detected in the other printing unit, the plate may be removed with its end portion being detached from the plate cylinder, or the plate remains substantially unremoved with its end portion being held by the plate cylinder.
If, in this state, the plate cylinder is rotated in a normal or reverse direction to remove the plate of the printing unit showing the abnormality in the plate removal, the plate cylinders of all printing units are rotated in the normal or reverse direction in an interlocked manner. Thus, damage may be caused to the printing plate of other printing unit where no abnormality in the plate removal was detected when the abnormality was detected. To remove the damaged printing plate, many man-hours and much time are required. Similar problems are posed when an abnormality in the plate being supplied occurs during a plate supply operation for automatically mounting printing plates on plate cylinders.
The present invention has been conceived to solve the above problems. Its object is to provide a plate handling method and a plate handling apparatus for a printing press having a plurality of printing units, the method and the apparatus being constituted such that during a plate removal or plate supply operation for the erring unit where an abnormality in the plate removal or plate supply was detected, a plate removal or supply operation for the other normal units can be performed continuously, whereby the plate removal or supply can be carried out reliably in a short period of time.
To attain the above object, there is provided, according to an aspect of the present invention, a plate handling method of a printing press having plate handling apparatuses, the printing press having a plurality of printing units, each printing unit having a plate cylinder, a drive device for driving all of the plate cylinders, and clutches disposed between the drive device and the printing units for transmitting and cutting off a drive force from the drive device to the printing units, and the printing press being adapted to rotate the plate cylinders by the drive from the drive device and cause the plate handling apparatuses to insert plates into the plate cylinders or remove the plates from the plate cylinders, the plate handling method comprising:
disengaging the clutch of the printing unit, where an abnormality in supply or removal of the plate was detected by any of detectors provided in the each printing unit for detecting the abnormality in supply or removal of the plate, to cut off the drive force from the drive device;
and allowing the drive force from the drive device to remain transmitted in the other printing units, thereby continuing supply or removal of the plates in the other printing units.
In the plate handling method of the printing press, the plate handling apparatus may comprise an actuator for driving a moving plate guide, a plate dismounting actuator for driving a plate dismounting guide, and a plate press roller actuator for driving a plate press roller, and may inhibit the three actuators from acting in case of the abnormality in supply or removal of the plate.
In the plate handling method of the printing press, an alarm may be issued by a warning device in the printing unit where the abnormality in supply or removal of the plate was detected.
According to another aspect of the present invention, there is provided a plate handling apparatus of a printing press, the printing press having a plurality of printing units, each printing unit having a plate cylinder, a drive device for driving all of the plate cylinders, and clutches disposed between the drive device and the printing sections for transmitting and cutting off a drive from the drive device to the printing units, the plate handling apparatus comprising: detectors provided in the each printing unit for detecting an abnormality in supply or removal of the plate; and a control device for disengaging the clutch of the printing unit, where the abnormality in supply or removal of the plate was detected by any of the detectors, to cut off the drive by the drive device, and allowing drive force from the drive device to remain transmitted in the other printing units, thereby continuing supply or removal of the plates in the other printing units.
The plate handling apparatus of the printing press may comprise an actuator for driving a moving plate guide, a plate dismounting actuator for driving a plate dismounting guide, and a plate press roller actuator for driving a plate press roller, and the control device may inhibit the three actuators from acting in case of the abnormality in supply or removal of the plate.
The plate handling apparatus of the printing press may include a warning device in each of the printing units, and the control device may exercise control such that if the abnormality in supply or removal of the plate is detected by any of the detectors, the warning device in the printing unit concerned issues an alarm.
According to the plate handling method and apparatus of the present invention, the drive force from the drive device to the printing unit, where an error (abnormality) during plate changing has occurred, is cut off, but a plate changing operation for the other printing units is continued. Thus, the plate changing time can be shortened, and damage to the plate, plate cylinder, and surrounding devices in the printing unit undergoing the error can be minimized.